Enhancing and preserving anti-microbial performance in fibers with pigments

ABSTRACT

A method for producing fibers with improved color and anti-microbial properties is described. One embodiment includes a method for generating a halogen stable anti-microbial synthetic fiber, the method comprising creating a mixture that includes a polymer, an anti-microbial agent, and a non-halogen pigment, and extruding the mixture to form an anti-microbial synthetic fiber.

PRIORITY

This application is a divisional of U.S. application Ser. No. 13/276,069, filed Oct. 18, 2011, which claims the benefit of U.S. Provisional Application No. 61/394,242, filed Oct. 18, 2010, both of which are incorporated herein by reference in their entirety for all purposes.

FIELD OF THE INVENTION

The present invention relates to fibers and fabrics designed for the effective destruction of pathogens such as bacteria, mold, mildew, fungus, spores and viruses.

BACKGROUND OF THE INVENTION

Anti-microbial additives containing copper, silver, gold, and zinc, either individually or combined, have been effective against pathogens such as bacteria, mold, mildew, virus, spores, and fungus. Accordingly, fibers and fabrics have been produced with anti-microbial alloys in various synthetic polymers such as polyester, polypropylene, nylon, rayon, and polylactic acid (PLA). There are many uses and applications for these types of anti-microbial fibers and fabrics, including the healthcare industry, hospitality industry, military, and infant care, among others. However, current anti-microbial fibers and fabrics have shortcomings in meeting the requirements of these uses and applications.

For example, in the healthcare and hospitality industry—such as in a hospital, nursing homes, extended care facilities, hotels, spas or the like—it is required that privacy curtains, isolation gowns, sheets, towels, scrubs, doctor's coats, bath robes, pajamas, and uniforms for medical personnel, both be sanitary and be perceived as sanitary. Therefore, the healthcare and hospitality industries require that these fabrics and garments conform to certain sanitation criteria. As there has been a rise in the possibility of contracting various contagious diseases such as Methicillin-resistant Staphylococcus aureus (MRSA) over the past few years, most in the healthcare industry now require bleaching of the towels, garments and other fabrics used in hospitals and various places where repeated use of the towels, garments and fabrics will, or is likely to, occur. This, of course, eliminates many of the types and colors of towels, garments and fabrics that can be used in the healthcare industry and is one reason why most of the fabrics are white. Moreover, because fibers and fabrics produced with known methods lose their effectiveness during repeated launderings with chlorine bleach, the laundering process required in these industries causes issues with known anti-microbial fibers and fabrics.

While the selection of white fabrics can be beneficial because of the repeated launderings, additives of copper, silver, gold, and zinc will discolor the fibers and fabrics during the life of the product, primarily due to oxidation. Accordingly, there is a need to add coloration to hide the undesirable shades created by the oxidation of the additives. In some cases, pigments have been used to color synthetic fibers by adding the pigments to the molten polymer of thermoplastic resins such as polyester, polypropylene, nylon, acrylic, or PLA. But in many cases pigments have been shown to have destructive effects on anti-microbial performance. These destructive effects are only increased due to bleach treatments that are commonly used on sanitary fabrics.

Thus the need exists for an anti-microbial fabric that will resist the destructiveness of washing in chlorine bleach and maintain its color and efficacy against pathogens. Although present fabrics and methods of making fabrics are functional, they are not sufficiently effective or otherwise satisfactory. Accordingly, a system and method are needed to address the shortfalls of present technology and to provide other new and innovative features.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention that are shown in the drawings are summarized below. These and other embodiments are more fully described in the Detailed Description section. It is to be understood, however, that there is no intention to limit the invention to the forms described in this Summary of the Invention or in the Detailed Description. One skilled in the art can recognize that there are numerous modifications, equivalents and alternative constructions that fall within the spirit and scope of the invention as expressed in the claims.

In an embodiment, the present invention comprises a method for generating a halogen stable anti-microbial synthetic fiber, the method comprising creating a mixture, the mixture comprising a polymer, an anti-microbial agent, and a cationic pigment; and extruding the mixture to form an anti-microbial synthetic fiber. The cationic pigment may also be a non-halogen pigment, include halogen bonding sites that attract chlorine or other halogens known to be detrimental to anti-microbial fibers, and/or include an element with known anti-microbial properties. In certain embodiments, the cationic pigment may be Phthalo Blue. In yet further embodiments, Titanium Dioxide may be added to the mixture with the Phthalo Blue cationic pigment.

In another embodiment, the present invention comprises a synthetic fiber comprising a polymer, an anti-microbial agent, and a cationic pigment. The cationic pigment may also be a non-halogen pigment, include halogen bonding sites, and/or include an element with known anti-microbial properties. In certain embodiments, the cationic pigment may be Phthalo Blue. The synthetic fiber can have a density of 0.4 to 25 denier, and specifically 1.0 to 1.5 denier in some embodiments. The fiber may be in continuous form or cut to a staple length from 0.25″ to 7.5″ (6 mm to 190 mm), and specifically 1.5″ (38 mm) or 2″ (51 mm). In yet another embodiment, the fiber may be part of a continuous filament nonwoven fabric, such as a spunbond or spunmelt fabric.

As previously stated, the above-described embodiments and implementations are for illustration purposes only. Numerous other embodiments, implementations, and details of the invention are easily recognized by those of skill in the art from the following descriptions and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Various objects and advantages and a more complete understanding of the present invention are apparent and more readily appreciated by reference to the following Detailed Description and to the appended claims when taken in conjunction with the accompanying Drawings wherein:

FIG. 1 includes a flow chart for an exemplary method of producing fibers consistent with an embodiment of the present invention.

FIG. 2 shows the molecular structure of Phthalo Blue pigment, with the copper molecule at its core.

FIG. 3 shows the molecular structure of Phthalocyanine Green G pigment with 15 chlorine molecules.

FIG. 4 shows the molecular structure of Phthalo Green 36 pigment with a combination of 16 chlorine and bromine molecules.

DETAILED DESCRIPTION

Referring now to the drawings, where like or similar elements are designated with identical reference numerals throughout the several views, and referring in particular to FIG. 1, it illustrates a method for manufacturing colored fibers with improved anti-microbial performance. At Step 100 a mixture is created, the mixture including a polymer, an anti-microbial alloy powder, and a cationic pigment. As used herein, a polymer refers to a compound suitable for fiber and fabric generation including, but not limited to, a thermoplastic polymer, polyester, nylon, rayon, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETG), co-PET, polylactic acid (PLA), and polytrimethylene terephthalate (PTT). In a preferred embodiment, the polymer may be polyester for durability, wrinkle resistance and color retention or nylon for its anti-drip, slow burn properties.

An anti-microbial agent may be any suitable anti-microbial, such as silver, copper, zinc and/or gold in metallic forms (e.g., particulates, alloys and oxides), salts (e.g., sulfates, nitrates, acetates, citrates, and chlorides) and/or in ionic forms. In some embodiments, the anti-microbial agent is an anti-microbial alloy powder with a particle size of less than 1 micron, and preferably 0.3 to 0.6 micron.

The anti-microbial agent may be comprised of an anti-microbial powder formed from alloys of one or more metals that exhibit anti-microbial properties. Anti-microbial alloys made of two or more element alloys can have superior anti-microbial properties compared to one element particles. Embodiments of the present invention can include an anti-microbial alloy which includes a combination of: transition metals of the periodical table such as chromium, manganese, iron, cobalt, nickel, copper, zinc, silver, and/or gold; rare earth metals from the lanthanides such as cerium, neodymium, samarium, gadolinium, terbium, dysprosium, holmium, and/or erbium; and/or alkali metals such as lithium, sodium, potassium, magnesium, and/or calcium. The combination may comprise a binary combination, ternary combination, quaternary combination, or even higher order combination. The selected alloys, and the relative percentages of each alloy, may be selected depending on the intended use of the fiber or other selection criteria. Different combinations will result in different anti-microbial classes that may be used with the present invention.

For example, different classes of anti-microbial alloys have been produced by QuarTek Corporation as described in various patent applications (U.S. Provisional Application Nos. 60/888,343 and 60/821,497 filed on Aug. 4, 2006 and U.S. patent application Ser. Nos. 11/868,475 filed on Oct. 6, 2007, 11/858,157 filled on Sep. 20, 2007, and 11/671,675 filed on Feb. 6, 2007). These anti-microbial alloys have been produced by varying the elemental composition of the alloys, the elemental ratios within the same alloy, or by changing parameters in the synthesis process. As needed, these anti-microbial alloys may be synthesized in various size ranges from 5 nm to 2000 nm, preferably less than 1000 nm, or even within the range of 100-500 nm.

A cationic pigment is a pigment which has a positively charged molecular structure. In a preferred embodiment, the cationic pigment is a non-halogen pigment which does not include halogens such as chlorine, bromine or fluorine in its molecular structure. In another embodiment, the cationic pigment further includes halogen bonding sites that can attract chlorine or other halogens that may come into contact with the fiber, such as during laundering. These halogen bonding sites can attract and connect to a chlorine molecule or other halogen molecules and protect the alloys of copper, silver, gold, and/or zinc that provide the anti-microbial properties to the fiber. In yet further embodiments, the cationic pigment may be selected because it comprises an element with known anti-microbial properties.

For example, a preferred cationic pigment is Phthalo Blue Pigment (Phthalocyanine Blue), which has a molecular structure C₃₂H₁₆CuN₈ as shown in FIG. 2. Phthalo Blue was chosen because, as shown in FIG. 2, it does not include a halogen, contains a Copper molecule in its core, and has 16 available sites that can attract halogen molecules such as chlorine. A halogen molecule such as chlorine can replace a hydrogen molecule and protect the alloys of copper, silver, gold, and zinc. In addition, Phthalo Blue is a brilliant blue pigment which resists fading due to bleach and sunlight. It has excellent hiding power and prevents any discoloration from the oxidation of copper, silver, or zinc. In some embodiments, Titanium Dioxide may also be added because it has excellent hiding power and softens the strong blue of Phthalo Blue. Titanium Dioxide also does not contain any chlorine molecules.

Other non-halogen pigments that may be selected include:

-   -   Egyptian Blue (Calcium Copper Silicate) CaCuSi₄O₁₀     -   Vermillion (Mercury Sulfide) HgS     -   Iron Oxide Red FeO     -   Ultramarine Blue Na₂OSAl₂SiO₆     -   Han Purple BaCuSi₂O₆     -   Paris Green (Aceto-arsenite) ({CuC₂H₃O₂}₂-3Cu(AsO₂)₂)     -   Sheele's Green (Copper Arsenite) CuHA₅O₅

As indicated by Step 200 in FIG. 1, once the mixture is created, the mixture may be extruded in order to create a fiber. The extrusion process itself depends on the temperature of the mixture being sufficiently high to melt the mixture. A melting step may be a separate step in FIG. 1 or it may be part of either the mixing process or the extruding process. When the mixture is at a sufficiently high temperature, the mixture may be extruded using conventional mechanisms such as a spinneret. The fiber may then be drawn, crimped, cut and spun into a yarn or other fabric depending on the intended end use (Step 300).

An exemplary fiber consistent with the present invention was made with between 99.3% and 99.6% Polyester (PET) resin, between 0.1% and 0.4% QuarTek Alloy QSM-ACL73 and 0.3% Phthalo Blue pigment. In some embodiments, Titanium Dioxide may also be added. The compounds were extruded at a melt temperature of 290° C. and pumped through a 2400 hole spinneret to produce a fiber of 5.5 denier. The fiber was then drawn to 1.5 denier, crimped, and cut to 1.5″ (38 mm). These exemplary fibers exhibit improved visual properties and improved anti-microbial effectiveness after launderings. Fibers produced with these pigments had very poor anti-microbial properties.

In accordance with the present method, pigments such as Phthalocyanine Green G (molecular structure is shown in FIG. 3) and Phthalo Green 36 (molecular structure is shown in FIG. 4) will not be used because they contain chlorine molecules which adversely affect the anti-microbial properties of a resultant fiber.

In conclusion, the present invention provides, among other things, method for producing fibers with improved color and anti-microbial properties. Those skilled in the art can readily recognize that numerous variations and substitutions may be made in the invention, its use and its configuration to achieve substantially the same results as achieved by the embodiments described herein. Accordingly, there is no intention to limit the invention to the disclosed exemplary forms. Many variations, modifications and alternative constructions fall within the scope and spirit of the disclosed invention as expressed in the claims. 

What is claimed is:
 1. A method for generating a halogen stable anti-microbial synthetic fiber, the method comprising: creating a mixture, the mixture comprising a polymer, an anti-microbial agent, and a non-halogen pigment; and extruding the mixture to form an anti-microbial synthetic fiber.
 2. The method of claim 1, wherein the polymer is selected from a group consisting of a thermoplastic polymer, polyester, nylon, rayon, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETG), co-PET, polylactic acid (PLA), and polytrimethylene terephthalate (PTT).
 3. The method of claim 1, wherein the non-halogen pigment includes halogen bonding sites.
 4. The method of claim 1, wherein the non-halogen pigment comprises an element with known anti-microbial properties.
 5. The method of claim 1, wherein the non-halogen pigment is Phthalo Blue.
 6. The method of claim 1, wherein the mixture further comprises Titanium Dioxide.
 7. The method of claim 1, wherein the non-halogen pigment is selected from the group consisting of CaCuSi₄O₁₀, HgS, FeO, Na₂OSAl₂SiO₆, BaCuSi₂O₆, ({CuC₂H₃O₂}₂-3Cu(AsO₂)₂), and CuHA₅O₅.
 8. The method of claim 1, wherein: creating the mixture comprises mixing polymer pellets, the non-halogen pigment, and the anti-microbial alloy powder in a mixer; and extruding the mixture to form the anti-microbial synthetic fiber comprises: heating the mixture to a melt temperature; and pumping the mixture through a spinneret.
 9. The method of claim 1, further comprising: using the anti-microbial fiber to create a fabric. 